This movie was shot entirely in color. It was decided during editing, however, that the movement between past and present could be made clearer by printing the Roman and Margaret scenes in black-and-white. Director Sir Kenneth Branagh comments on the DVD that the costume and set designers were disappointed by this, because they would have used different colors for those scenes, which would photograph better in black-and-white, had they known this.
Two additional double roles (besides Mike/Roman and Grace/Margaret) are in this movie: the nun at the orphanage turns up as a snooty starlet at a party in the 1940s, and the cop at the mental hospital is seen again as an obnoxious party guest.
When we first meet Mike Church, he's parked on the wrong side of the street. Most people thought this was a nod to director Sir Kenneth Branagh's British heritage. The real reason is because Branagh wanted some Los Angeles skyscrapers visible in the background.
Being one of his few horror/thriller movies, Robin Williams didn't want his name to appear in the opening credits, as it might have misled audiences into thinking that this movie was a comedy. He only has three scenes with director Sir Kenneth Branagh, and one with Dame Emma Thompson. This was due to Robin doing two other movies the same year, not from Paramount Pictures, but from TriStar Pictures (a subsidiary of Sony Pictures), which include Terry Gilliam's Fisher King - Le roi pêcheur (1991) and Steven Spielberg's Hook ou la Revanche du capitaine Crochet (1991)
The convent is the same building that was used for exteriors of Bruce Wayne's house in Batman (1966).
Patrick Doyle: The movie's composer played the bored cop in the elevator, and the obnoxious guest at Otto's party.
Scott Frank: Uncredited, the film's screenwriter as one of the cops in the elevator at the mental hospital.
Kenneth Branagh: [William Shakespeare )]: The cover of the LIFE magazine in Mr. Madson's shop shows Laurence Olivier in Hamlet (1948); another Shakespeare reference is on the bridge where Mike and Doug fight (it reads "Shakespeare Bridge," the real name of a bridge in L.A. where the movie was filmed).